I buy ebooks from google play but don't use it as a reader just transfer to calibre and then to my reader. I opened google play just to check if it shows any ads don't see any so far. Looking at apkmirror maybe 5 or 6 updates have been uploaded in the last week. Here is the list of versions that are available. If any one wants to try these are unmodified apks so wont break your link with google play and you will still get update if and when the newer version comes
http://www.apkmirror.com/apk/google-...-apk-download/
I tried the latest version still not seeing any ads